This invention relates to devices for proportioning a gaseous fuel and air for combustion in an internal combustion engine. In one aspect, the invention relates to such devices which can be mounted on the air intake of the existing carburetor of an internal combustion engine to provide the engine with the capability of being operated on either a liquid fuel or a gaseous fuel.
Systems for providing internal combustion engines with the capability of operating on either liquid fuel, such as gasoline, or a gaseous fuel, such as natural gas, typically include a so-called gas mixer which fits onto the air intake of the existing carburetor and proportions the gaseous fuel and air in the proper ratio for combustion. Some prior gas mixers are so large that the existing air cleaner and/or manifold heating system must be removed with resultant warm-up problems when the engine is operated on gasoline. Other gas mixers restrict air flow and require some mechanical means for selectively increasing the air flow area when the engine is operated on gasoline.